[menage]

But cross-contamination in a shared production facility can happen fairly easily (and is important for folks who are sensitive to a few parts-per-million of gluten), hence why lots of packets have that warning in the small print. An obvious "gluten-free" label means that the producer is asserting that this cross-contamination hasn't occurred and you don't have to search the small print.

[larkost]

From what I understand gluten intolerance (including Celiac disease) is not at all like allergies where even a small amount of cross contamination can be harmful (or even deadly). Gluten intolerance really needs a solid amount (which many foods provide) to trigger problems, and the worry is really the long-term damage that can be done.

So I think that the "gluten-free" labels on things that obviously would not have gluten in them (e.g.: bottled water) is absolutely about advertisement to people who have been trained to think that "gluten-free" is always a good thing.

[menage]

Celiac disease and Non-Celiac Gluten Sensitivity are very different beasts in terms of their effects. The latter is more likely to triggered in the presence of (as you say) non-trivial amounts of gluten; Celiac disease is an auto-immune disease that, while not normally at the level of anaphylactic shock, can have very unpleasant effects in tiny amounts.

And even within Celiac disease there are a lot of variations. My mother has been diagnosed as Celiac for 50 years (back before most doctors had heard of it, and she almost died from malnutrition pre-diagnosis). She obviously avoids anything that has any mention of wheat, or has been cooked in the same oil as glutenous food; she generally avoids anything that mentions "possible cross-contamination" on the label but doesn't have to be a total stickler. I don't think she's had a serious attack in many years. A friend of mine was diagnosed as Celiac maybe 10 years ago, and is incredibly sensitive - despite his best efforts he seems to end up with horrible symptoms every couple of months or so just through tiny amounts of contamination.

The FDA limit for claiming something is "gluten-free" is 20 ppm; I believe that level exists partly because it's very hard to detect anything less than that anyway, but it also fits in well with what most Celiac sufferers can tolerate.

[cratermoon]

That's true, and I made a conscious decision not to mention cross-contamination, knowing that the hn community would fill in the gaps.

The short answer is that no, the label gluten free alone does not say anything about cross-contamination.